1. Field of the Invention
The present invention relates to an ophthalmic imaging apparatus having blink detection function and control method thereof.
2. Description of the Related Art
Regarding a fundus camera as an ophthalmic imaging apparatus, the fundus camera having a blink function is proposed. The fundus camera detecting the blink is described in Japanese Patent No. 60-057853 (hereafter, document 1) by disposing a special photo-detection means at the position, receiving reflected light from an anterior segment of the eye to be examined in the fundus camera optic system, and detecting change in the quantity of reflected light. Moreover, the ophthalmic imaging apparatus proposed in Japanese Patent No. 06-013022 (hereafter, document 2) obtains a fundus image illuminated by near-infrared light emitted from an observation light source, by using a two-dimensional image sensing device and a blink is detected by an outgoing signal of the fundus image. According to the detection result, the ophthalmic imaging apparatus permits or prohibits obtaining the fundus image by a separated imaging means.
In addition, a fundus camera, which obtains an image of an object by an image sensing device and controls an aperture of the optical system by using the signal of the image, is proposed. A fundus camera proposed in Japanese Patent Laid-Open No. 08-001022 (hereafter, document 3) changes the size of the shading part installed in the state of optical conjugate with the anterior segment of the eye to be examined in illumination optics according to the result of the means for inputting or detecting a pupil diameter of the eye to be examined, and can illuminate even the small pupil system.
However, there has been a problem in that the device configuration becomes complicated to provide the blink detection function in the fundus cameras described in document 1 and document 2 mentioned above. For instance, a special blink detection sensor is necessary in the fundus camera that has the blink detection function described in document 1. Moreover, in the fundus camera described in document 2, even though the observation image sensing device that outputs the moving image and the means for blink detection are shared, a capturing means for still image is separately needed.
In addition, the detection accuracy decreases if the imaging means and detection sensors are separately arranged and there is a relative position misalignment between imaging means and detection sensors, as mentioned above. Therefore, it is necessary to apply severe accuracy to each component or to perform adjustment work by using the adjustment mechanism to eliminate relative position misalignment. As a result, the cost of the device rises.
In addition, a means for detecting a pupil diameter is also necessary for the fundus camera, which changes a light blocking part that is arranged in an illumination optical system according to the pupil diameter of the eye to be examined described in document 3. Therefore, when combining with blink detection function mentioned above, the structure of the fundus camera may be complicated. Moreover, when the means for inputting the pupil diameter is used, instead of means for detecting the pupil diameter, a problem rises where inappropriate image capturing may be performed because of an increase of user's operations and user's input error.